Metacat

/**

 *  Copyright: 2013 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package edu.ucsb.nceas.metacat.common.query;

import java.io.IOException;

import java.io.InputStream;

import java.net.MalformedURLException;

import java.net.URL;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.Vector;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.xpath.XPathConstants;

import javax.xml.xpath.XPathExpressionException;

import javax.xml.xpath.XPathFactory;

import org.apache.commons.codec.net.URLCodec;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.apache.solr.client.solrj.impl.CommonsHttpSolrServer;

import org.apache.solr.client.solrj.util.ClientUtils;

import org.apache.solr.common.params.SolrParams;

import org.apache.solr.core.SolrConfig;

import org.apache.solr.schema.FieldType;

import org.apache.solr.schema.IndexSchema;

import org.apache.solr.schema.SchemaField;

import org.apache.solr.schema.TextField;

import org.dataone.configuration.Settings;

import org.dataone.service.exceptions.NotFound;

import org.dataone.service.exceptions.NotImplemented;

import org.dataone.service.types.v1.Subject;

import org.w3c.dom.Attr;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

import org.xml.sax.Attributes;

import org.xml.sax.InputSource;

import org.xml.sax.SAXException;

/**

 * The query service for the http solr server.

 * @author tao

 *

 */

public class HttpSolrQueryService extends SolrQueryService {

    private static final String SELECTIONPHASE = "/select";

    private static final String SOLR_SYSTEMINFO_URLAPPENDIX = "solr.systeminfo.urlappendix";

    private static final String SOLR_SCHEMA_URLAPPENDIX = "sorl.schema.urlappendix";

    private static final String SOLR_CONFIG_URLAPPENDIX = "solr.config.urlappendix";

    private static final String SPEC_PATH = "//str[@name='solr-spec-version']";

    private static final String FIELDS_PATH = "//fields//field";

    private static final String COPY_FIELDS_PATH = "//copyField";

    private static final String DEST = "dest";

    private static final String TRUE = "true";

    private String solrServerBaseURL = null;

    private CommonsHttpSolrServer httpSolrServer = null;

    private static Log log = LogFactory.getLog(HttpSolrQueryService.class);

    /**

     * Constructor

     * @param httpSolrServer

     */

    public HttpSolrQueryService(CommonsHttpSolrServer httpSolrServer) {

        if(httpSolrServer == null) {

            throw new NullPointerException("HttpSolrQueryService.constructor - The httpSolrServer parameter can't be null");

        }

        this.httpSolrServer = httpSolrServer;

        this.solrServerBaseURL = httpSolrServer.getBaseURL();

    }

    /**

     * Query the Solr server with specified query string and the user's identity. This is the for the http solr server.

     * It is hard to transform the SolrQueryReponse object to the InputStream object for the HttpSolrServer

     * since the transform needs the SolrCore. We have to open the solr url directly to get the InputStream.

     * @param query the query string

     * @param subjects the user's identity which sent the query

     * @return the response

     * @throws NotFound 

     * @throws IOException 

     * @throws Exception

     */

    /*public InputStream query(String query, Set<Subject>subjects) throws NotFound, IOException {

        StringBuffer accessFilter = generateAccessFilterParamsString(subjects);

        if(accessFilter != null && accessFilter.length() != 0) {

            query = solrServerBaseURL+"/select?"+query+"&"+FILTERQUERY+"="+accessFilter.toString();

            query = ClientUtils.escapeQueryChars(query);

        } else {

            throw new NotFound("0000", "HttpSolrQueryService.query - There is no identity (even user public) for the user who issued the query");

        }

        log.info("==========HttpSolrQueryService.query - the final url for querying the solr http server is "+query);

        URL url = new URL(query);

        return url.openStream();

    }*/

    /**

     * Query the Solr server with specified query and user's identity. 

     * It is hard to transform the SolrQueryReponse object to the InputStream object for the HttpSolrServer

     * since the transform needs the SolrCore. We have to open the solr url directly to get the InputStream.

     * @param query the query params. 

     * @param subjects the user's identity which sent the query. If the Subjects is null, there wouldn't be any access control.

     * @return the response

     * @throws IOException 

     * @throws NotFound 

     * @throws Exception

     */

    public  InputStream query(SolrParams query, Set<Subject>subjects) throws IOException, NotFound {

        boolean xmlFormat = false;

        String queryString = ClientUtils.toQueryString(query, xmlFormat);

        log.info("==========HttpSolrQueryService.query - the query string after transforming from the SolrParams to the string "+queryString);

        StringBuffer accessFilter = generateAccessFilterParamsString(subjects);

        if(accessFilter != null && accessFilter.length() != 0) {

            String accessStr = accessFilter.toString();

            log.debug("==========HttpSolrQueryService.query - the access string is "+accessStr);

            URLCodec urlCodec = new URLCodec();

            accessStr = urlCodec.encode(accessStr, "UTF-8");

            log.debug("==========HttpSolrQueryService.query - the access string after escape special characters string "+accessStr);

            queryString = queryString+"&"+FILTERQUERY+"="+accessStr;

        }

        //queryString = ClientUtils.escapeQueryChars(queryString);

        queryString = solrServerBaseURL+SELECTIONPHASE+queryString;

        log.info("==========HttpSolrQueryService.query - the final url for querying the solr http server is "+queryString);

        URL url = new URL(queryString);    

        return url.openStream();

        //throw new NotImplemented("0000", "HttpSolrQueryService - the method of  query(SolrParams query, Set<Subject>subjects) is not for the HttpSolrQueryService. We donot need to implemente it");

    }

    /**

     * Get the fields list of the index schema

     * @return

     * @throws SAXException 

     * @throws IOException 

     * @throws ParserConfigurationException 

     * @throws MalformedURLException 

     * @throws Exception

     */

    public  Map<String, SchemaField> getIndexSchemaFields() throws MalformedURLException, ParserConfigurationException, IOException, SAXException  {

        if(fieldMap == null || fieldMap.isEmpty()) {

            getIndexSchemaFieldFromServer();

        }

        //System.out.println("get filed map ==========================");

        return fieldMap;

    }

    /**

     * Get the list of the valid field name (moved the fields names of the CopyFieldTarget).

     * @return

     * @throws SAXException 

     * @throws IOException 

     * @throws ParserConfigurationException 

     * @throws MalformedURLException 

     */

    public List<String> getValidSchemaField() throws MalformedURLException, ParserConfigurationException, IOException, SAXException {

        if(fieldMap == null || fieldMap.isEmpty()) {

            getIndexSchemaFields();

        }

        return super.getValidSchemaFields();

    }

    /*

     * Get the fieldMap from the http server. 

     * @throws MalformedURLException

     * @throws ParserConfigurationException

     * @throws IOException

     * @throws SAXException

     */

    private void getIndexSchemaFieldFromServer() throws MalformedURLException, ParserConfigurationException, IOException, SAXException {

        //System.out.println("get filed map from server (downloading files) ==========================");

        SolrConfig config = new SolrConfig("dataone", new InputSource(getSolrConfig())); 

        schema = new IndexSchema(config, "dataone", new InputSource(getSchema()));

        fieldMap = schema.getFields();

    }

    /*

     * Parse the schema.xml and get the validSolrFieldName list

     */

    /*private void parseSchema() throws MalformedURLException, ParserConfigurationException, SAXException, IOException, XPathExpressionException {

        validSolrFieldNames = new ArrayList<String>();

        Map<String, SchemaField> fieldMap = new HashMap<String, SchemaField>();

        Document schema = transformInputStreamToDoc(getSchema());

        Vector<String>copyFieldTargetNames = new Vector<String>();

        NodeList copyFields = (NodeList) XPathFactory.newInstance().newXPath()

                        .evaluate(COPY_FIELDS_PATH, schema, XPathConstants.NODESET);

        if(copyFields != null) {

            for(int i=0; i<copyFields.getLength(); i++) {

                Element copyField = (Element)copyFields.item(i);

                String target = copyField.getAttribute(DEST);

                if(target != null && !target.trim().equals("")) {

                    copyFieldTargetNames.add(target);

                }

            }

        }

        NodeList fields = (NodeList) XPathFactory.newInstance().newXPath()

                        .evaluate(FIELDS_PATH, schema, XPathConstants.NODESET);

        if(fields!= null) {

            for(int i=0; i<fields.getLength(); i++) {

                Element fieldElement = (Element) fields.item(i);

                String name = fieldElement.getAttribute("name");

                if(name != null && !name.trim().equals("")) {

                    if(!copyFieldTargetNames.contains(name)) {

                        validSolrFieldNames.add(name);

                    }

                }

            }

        }

    }*/

    /*

     * Get the SolrConfig InputStream.

     * @return

     * @throws MalformedURLException

     * @throws IOException

     */

    private InputStream getSolrConfig() throws MalformedURLException, IOException {

        String solrConfigAppendix = Settings.getConfiguration().getString(SOLR_CONFIG_URLAPPENDIX);

        String configURL = solrServerBaseURL+solrConfigAppendix;

        return (new URL(configURL)).openStream();

    }

    /*

     * Get the schema InputStream from the url which is specified in the metacat.properties and transform it to a Document.

     */

    private InputStream getSchema() throws MalformedURLException, IOException {

        String schemaURLAppendix = Settings.getConfiguration().getString(SOLR_SCHEMA_URLAPPENDIX);

        String schemaURL = solrServerBaseURL+schemaURLAppendix;

        return (new URL(schemaURL)).openStream();

    }

    /**

     * Get the version of the solr server.

     * @return

     */

    public String getSolrServerVersion() {

        if(solrSpecVersion == null) {

            getHttpSolrServerVersion();

        } 

        //System.out.println("get spec version  ==========================");

        return solrSpecVersion;

    }

    /*

     * Get the solr server version from the system information url. 

     */

    private void getHttpSolrServerVersion() {

        //System.out.println("get spec version from server (downloading files) ==========================");

        String systemInfoUrlAppendix = Settings.getConfiguration().getString(SOLR_SYSTEMINFO_URLAPPENDIX);

        String systemInfoUrl = solrServerBaseURL+systemInfoUrlAppendix;

        try {

            Document doc = transformInputStreamToDoc((new URL(systemInfoUrl)).openStream());

            NodeList nodeList = (NodeList) XPathFactory.newInstance().newXPath()

                            .evaluate(SPEC_PATH, doc, XPathConstants.NODESET);

            if(nodeList != null && nodeList.getLength() >0) {

                //System.out.println("nodelist is not null branch");

                Node specNode = nodeList.item(0);

                solrSpecVersion = specNode.getFirstChild().getNodeValue();

            } else {

                //System.out.println("nodelist is null branch");

                solrSpecVersion = UNKNOWN;

            }

        } catch (Exception e) {

            log.error("HttpSolrQueryService.getHttpSolrServerVersion - can't get the solr specification version since "+e.getMessage());

            solrSpecVersion = UNKNOWN;

        }

    }

    /**

     * Generate a Document from the InputStream

     * @param input

     * @return

     * @throws ParserConfigurationException

     * @throws SAXException

     * @throws IOException

     */

    private Document transformInputStreamToDoc(InputStream input) throws ParserConfigurationException, SAXException, IOException {

        DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();

        DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();

        Document doc = dBuilder.parse(input);

        return doc;

    }

}